This bit of news was in a RedWolf airsoft piece about the old shell-ejecting GBB CZ75:

They don't make them like they used to... No wait! In the summer of 2008 Marushin did announce that they are releasing another shell-ejecting GBB pistol, the Glock 21.

Very interesting! Modelguns aren't cheap or easy to find, and as far as I'm concerned this would be almost as good. Wonder what they'll run for.

I do have a shell-ejecting gas blowback Marushin uzi, but it's got problems- it uses plastic casings, and the gun itself is a nice heavy metal... but that means that the rim on the casings chips easily, especially since whenever it does jam it sprays cold gas on the plastic, making it more brittle. Combination of increasingly frequent jams and the rare, easily broken, and red-rubber-tipped casings made it not a very reliable or popular prop.